Tumor-derived transforming growth factor-beta 1 and interleukin-6 are chemotactic for lymphokine-activated killer cells

Abstract

Adherent lymphokine-activated killer (A-LAK) cells are purified IL-2 activated natural killer (NK) cells with potent anti-tumor cytotoxic activity. They have been used in the adoptive immunotherapy of metastatic cancers. However, it has been shown that intravenously transferred LAK cells have a poor homing capacity to tumor sites. For the present study, the effects of tumor-derived factors on the in vitro migratory capacity of A-LAK cells was investigated. In a micropore migration assay the conditioned medium from 3LL Lewis lung carcinoma cell cultures was found to exert a strong chemotactic, but not chemokinetic effect on A-LAK cells. This effect was partially inhibited by neutralizing antibodies against the cytokines TGF-beta 1 and IL-6. A combination of the 2 antibodies completely suppressed the chemotactic activity of tumor-cell-conditioned medium. Purified TGF-beta 1 and recombinant IL-6 were chemotactic for A-LAK cells. Biological activities of both cytokines were detectable in the tumor-cell-conditioned medium. The in vivo relevance of these findings, with respect to tissue infiltration of NK cells and LAK cells in inflammation or cancer, remains to be elucidated.